Thermal Gelation of Myofibrils from Pork, Beef, Fish, Chicken and Turkey

Myofibril gels with 5, 7, or 10% protein and 2% NaCl were prepared from pork, beef, fish, chicken and turkey muscles using a heating rate of 0.7°C/min and pH 6.0 to compare the thermal gelation properties of myofibrillar protein from different species. The force required to rupture gel (Pf), force required to move plunger through gel (Fp), viscosity index (Ni), and elasticity (Ea) increased and cooking loss decreased with increasing protein contents. Myofibrils of chicken breast and thigh had lower and fish and turkey thigh had higher cooking loss at protein contents of 7% or 10%.     

End-point Temperature (EPT) Affects N-Acetyl-β-D-Glucosaminidase Activity in Beef, Pork and Turkey

End-point tempcraturc (EPT) affected N-acetyl-β-D-glucosaminidase (NAGasc) activity in nonfrozcn and previously frozen cores and ground sampics of beef, pork, turkey breast and ground turkey leg muscle tissue. There was little loss of NAGase activity when heating the products to 40°C; however, as EPT increased from 40–70°C, them was (Pc0.05) loss of activity. At 70°C 90% of activity was lost in beef, 98% in pork, and 93 to 98% in turkey. Inactivation temperature values, IT50, (50% inactivation) were: beef, 59.8°C; pork, 53.4°C; turkey breast, 55.6°C; and turkey leg, 56.6°C.     

Thermal Gelation of Pork, Beef, Fish, Chicken and Turkey Muscles as Affected by Heating Rate and pH

Effects of heating rate (3°C or 0.7°C/min) and pH (5.5, 6.0, 6.5, or 7.0) on thermal gelation properties of different muscle systems were evaluated (10% protein, 2% NaCl) using pork, beef, fish, and chicken and turkey (breast and thigh) muscles. Results indicated that, at pH 6.5 and 7.0, force required to rupture the gel (Pf), force required to move plunger through the gel (Fp), and viscosity index (Ni), using a slow heating rate, were higher than with rapid heating. All muscles (except breast muscles with the slow heating rate) yielded higher (P<0.05) gel strength (Fp, Pf) at pH 6.0 than at the other pHs.     

Process and Characteristics for a Surimi-like Material Made from Beef or Pork

Beef or pork was chopped, screened, and washed; water was removed by centrifugation to make surimi-like, water-washed beef or pork. Processing parameters were evaluated to develop the optimum processing techniques to yield the most functional material. Regardless of fat content in the starting material, water-washed beef or pork contained <1% fat. Water-washed muscle was lighter (reduced redness and yellowness) than the original starting material but had more color than fish surimi. Washed beef or pork formed gels with greater hardness than commercial fish surimi above 55°C after heating at 0.5°C/min. Salt soluble protein of water-washed beef or pork was higher than that of commercial fish surimi.     

Physical, Chemical and Sensory Changes in Irradiated Fresh Pork Packaged in Modified Atmosphere

The effects of irradiation dose (0, 0.5 and 1.0 kGy), headspace oxygen (0, 10 and 20% O₂, balance nitrogen) and storage temperature (5, 15 and 25°C) on the physical, chemical and sensory changes in fresh pork were studied using factorial design experiments. Irradiation in the absence of oxygen extended the sensory shelf life of pork from 9 to 26 days at 5°C and from & lt; 2 to 2 days at 25°C. Oxygen in the package headspace combined with irradiation adversely affected physical, chemical and sensory characteristics of the end product.     

Color and Oxidative Rancidity of Gamma and Electron Beam-Irradiated Boneless Pork Chops

Color and oxidative rancidity were determined for chilled (3 ± 2°C) and frozen (?17 ± 3°C) boneless pork chops packaged in vacuum or air and irradiated to an absorbed dose of 0, 1.5 or 2.5 kGy (chilled) or 0, 2.5 or 3.85 kGy (frozen) of electron beam or cobalt⁶⁰ irradiation. Irradiation of vacuum-packaged chops produced redder, more stable (color and rancidity) product. More pronounced oxidative rancidity and less stable display color were noted for samples irradiated in aerobic packaging. Irradiation source had varying but limited effects on color and rancidity. Optimum packaging conditions can control color and rancidity changes in boneless chops, thereby enabling irradiation to be a useful intervention technology.     

Lipid Oxidation, Volatiles and Color Changes of Irradiated Pork Patties Affected by Antioxidants

Changes were measured in TBARS, color, and volatiles of irradiated (4.5 kGy) pork patties with antioxidants (sesamol, quercetin, rutin, BHT, and rosemary oleoresin) during 7 days storage at 4°C. Irradiation accelerated lipid oxidation of raw pork during storage. However, irradiation before cooking did not influence lipid oxidation of cooked pork during storage. Sesamol, quercetin, and BHT were effective in both irradiated raw and cooked pork during 7-days storage. Rosemary oleoresin and rutin were effective only in irradiated raw pork for 3 days. Hexanal, propanal and higher boiling components were well correlated (P < 0.01) with TBARS in cooked pork. Generation of volatiles was reduced by sesamol and quercetin, but the effects of antioxidants on color changes of raw pork patties were minor and inconsistent.     

Effects of Different Gas Compositions on the Color Estimations of MAP Packaged Pork Chops

This study was conducted to observe effects of different gas compositions on color of pork chops packaged in modified atmospheres. Gaseous compositions used were: MAP1 (75% O₂:25% CO₂); MAP2 (70% O₂:30%CO₂) and MAP3 (80% O₂:20% CO₂). Sensory evaluations of meat color and chemical properties (acid number, peroxide value, a_w, pH, TVB-N and TBARs), were carried on the 1^st, 5^th, 7^th, 9^th and 12^th day of storage. The sensory evaluations of chop color in different MAP compositions are analyzed in relation to storage period, measured chemical properties and instrumental determination of meat color using linear and multivariate linear regression analysis.     

Composition of Surimi-like Material from Beef or Pork

A surimi-like material was made from finely minced beef or pork by water washing followed by screening to remove connective tissue. Changes in component proteins, amino acid composition and vitamin, mineral and cholesterol content occurring during preparation were investigated. Total amino acid nitrogen contents of water-washed beef and pork were higher than those of the respective muscle by 7% and 6.5%. Among 16 amino acids measured, histidine and glycine decreased in both water-washed beef and pork, while others increased compared to original muscle. Thiamin content decreased after washing. Surimi-like beef and pork had less cytoplasmic minerals (K, Na, Mg) but more minerals associated with proteins or subcellular organelles (Ca, Cu, Zn, Fe). Fat content decreased, although cholesterol concentration was not changed by washing.     

Salt, Cryoprotectants and Preheating Temperature Effects on Surimi-like Material from Beef or Pork

Gel forming ability, measured by cooked gel hardness, and water-holding capacity of surimi-like pork were enhanced by addition of NaCl at 1.5 or 3% although 4.5% or 6% NaCl did not further increase hardness. Cooked gel strength was unaffected by freezing of beef or pork surimi-like materials for 48 hr. Addition of cryoprotectants (3% or 6% sorbitol, 3% glycerol, or 3% sucrose) before freezing had no effect on gel forming ability. Gel hardness was not increased by preheating prior to cooking. Preheating surimi-like pork at 50°C resulted in formation of weaker gels which corresponded to myosin proteolysis. Myosin heavy chain (mw 200 kD) decreased, and new peptide fragments of mw about 138 kD, 128 kD, 120 kD, 86 kD, 77 kD, and 64 kD appeared. Proteolysis was salt-dependent and occurred at pH 6.8–7.5.     

Sensory Analysis and Consumer Acceptance of Irradiated Boneless Pork Chops

Flavor, texture, and aroma were determined for chilled (3 ± 2°C) and frozen (–17 ± 3°C) boneless pork chops packaged in vacuum or air and exposed to an absorbed dose of 0, 1.5, or 2.5 kGy (chilled) or 0, 2.5, or 3.85 kGy (frozen) of electron beam and cobalt⁶⁰ irradiation. Irradiation (< 3.85 kGy) had minimal effects on aroma, flavor, and textural attributes in chilled and frozen boneless pork chops. Irradiation source had limited effects and packaging type had the greatest influence. Consumers reported no difference (P>0.05) between irradiated (2.5 kGy cobalt⁶⁰ irradiated, chilled, vacuum-packaged, boneless, pork chops) and control samples for overall acceptance, meatiness, freshness, tenderness and juiciness.     

Texture, Color and Sensory Characteristics of Ground Beef Patties Containing Bovine Blood Proteins

Three levels of bovine plasma (BP; 1.5, 2.5, 3.5%), red cell (RC; 0.5, 0.75, 1.0%) and decolorized red cell (DC; 0.75, 1.5, 2.25%) proteins were substituted for lean in ground beef patties. Increased RC decreased HunterLab L* and b* values and DC increased L* values, b* values, nonheme iron, and heme iron in uncooked and cooked patties. Soy-type flavors with BP, bloody and metallic flavors with RC and sour flavors with DC increased compared with control patties. Color, iron, cooking loss, and oxidative stability were minimally changed in ground beef with 0.5% RC, 0.75% DC, or 3.5% BP.     

Lactate Dehydrogenase Monoclonal Antibody Immunoassay for Detection of Turkey Meat in Beef and Pork

Relative epitope binding positions on turkey muscle LDH of four monoclonal antibodies (MAbs) was determined by comparing the absorbance by sandwich ELISA from different combinations of capture and biotinlabeled detector MAbs. Epitopes for MAbs E6B and B3C were close to each other. Binding of MAb B3C and G4D did not inhibit binding of D5E to LDH, thus a sandwich ELISA using D5E as capture MAb, and biotin-labeled B3C as detector MAb was developed. The LDH MAb sandwich ELISA detected 1% adulteration of turkey breast or thigh muscle in raw beef and pork.     

包装方式对减轻冷却猪肉辐照异味的影响

冷却猪肉分别经真空包装、保鲜膜包装、复合包装、气调包装等预处理后辐照2.8kGy剂量,低温4℃冷藏,研究包装方式对减轻猪肉辐照异味的影响。结果表明,复合包装和60%O_2+30%CO_2+10%N_2组合的气调处理均可有效去除猪肉辐照异味,其中60%O_2+30%CO_2+10%N_2组合的气调处理4.2kGy剂量辐照后异味达到不可察觉的程度。     

PSE(白肌)、RFN(正常)、DFD(黑干)3种质量猪肉冷藏期间的肉色稳定性

比较了PSE(白肌)、RFN(正常)、DFD(黑干)3种质量猪肉冷藏期间的肉色稳定性。宰后24h直接切块取样的3种质量猪肉(背最长肌)于(2±1)℃下避光透氧包装[O2透过率=2.06×10-3mL/(m2.h.Pa)]冷藏6d,采用色度计法测定了样品表面L*(亮度)值、a*(红色度)值、b*(黄色度)值、hueangle(色调角)值。从上述指标的变化研究了3种质量猪肉表面的肉色稳定性。3种质量猪肉表面肉色稳定性顺序为:DFD>RFN>PSE;a*值下降、hueangle值上升可反映肉色稳定性变差。     

中国与主要发达国家牛羊禽肉与猪肉比价分析

分析了1995年以来美国、欧盟、日本、韩国和我国猪牛羊禽肉价格走势。除日本外,其余国家牛肉和猪肉价格均呈上涨趋势;美国、欧盟和中国羊肉价格以及美国、欧盟、韩国和中国鸡肉均呈涨势。日本和韩国牛肉/猪肉比价显著高于其它国家,总体呈降势,美国、欧盟和中国则呈增加趋势。我国牛羊肉/猪肉比价季节性不明显。我国和韩国鸡肉/猪肉比价处于低位。     

Endpoint Temperature, Internal Cooked Color, and Expressible Juice Color Relationships in Ground Beef Patties

Ground beef patties from A- and E-maturity carcasses and imported trimmings were cooked to 55 to 77°C. Internal patty color became less red as endpoint temperature increased. However, some patties cooked to lower temperatures turned brown prematurely. Visual evaluation of internal patty color was not an accurate indicator of patty doneness. Raw material source had little effect on internal patty color. Expressible juices from imported trimmings were less red than those from A-and E-maturity carcasses. Expressible juice became less red and more yellow with increasing endpoint temperature; however, expressible juice never “ran clear.” A more appropriate guideline would be “cook until juices lack redness.”     

Gamma Irradiation Effects on Thiamin and Riboflavin in Beef, Lamb, Pork, and Turkey

A study was made of the loss of thiamin and riboflavin due to gamma irradiation of beef, lamb and pork longissimus dorsi, turkey breast and leg muscles. Thiamin losses averaged 11%/kiloGray (kGy) and riboflavin losses 2.5%kGy above three kGy. The rate of loss of thiamin in beef was higher than that in lamb, pork and turkey leg, but not turkey breast. with losses of 16%/kGy in beef and 8%/kGy in lamb. The rate of thiamin loss was not related to sulfhydryl, protein, moisture, fat or water content, pH or reducing capacity by redox titration. Loss of riboflavin was not different among species. Any detriment from such slight losses would seem to be more than compensated by the advantage of controlling bacteriological contamination by irradiation processing.     

Dietary Vitamin E Affects Lipid Oxidation and Total Volatiles of Irradiated Raw Turkey Meat

Breast and leg meat patties, prepared from turkeys fed diets containing 25, 200, 400 or 600 IU of dl-α-tocopheryl acetate (TA) per kg diet, were irradiated at 0 or 2.5 kGy with vacuum or loose packaging. The effects of dietary TA on storage stability and production of volatiles in irradiated raw turkey meat were determined. Dietary TA at > 200 IU/kg decreased lipid oxidation and reduced total volatiles of raw turkey patties after 7-days of storage. However, the antioxidant effects of dietary TA were more notable when the patties were loosely packaged than when vacuum-packaged. Irradiation increased lipid oxidation of raw turkey meats only when loosely packaged but had limited effects on formation of total volatiles after storage at 4°C for 7 days or longer.